The present invention relates to methods for fabricating tamper-apparent and authenticating labels, seals and tags (hereafter xe2x80x9clabelsxe2x80x9d) for use in securing commercial items, such as electric meters, medicine bottles, compact discs, or any other items for which tamper apparency and authenticity is of value. The present invention also relates to tamper-apparent authenticating labels, seals and tags made by those methods.
Self-destructing labels are used to seal, protect and authenticate many commercial articles. The newest and most secure self-destructing labels are those which incorporate optically variable devices (xe2x80x9cOVD""sxe2x80x9d) including but not limited to diffraction gratings, exelgrams, kinegrams and/or holograms. A number of such labels are known, and are attachable to commercial articles by various means. For example, self-destructing labels can be hot-stamped or pressure-sensitive labels, with additional patterned adhesive underneath them.
If such a label is placed at the opening of a container, for instance a jewel case containing a compact disc, it is possible to tell if the product is genuine by viewing the OVD incorporated into the label sealing the jewel box. Removing the label causes the label to self-destruct into a pattern of smaller pieces. Thus, a counterfeiter cannot remove a genuine compact disc and place a counterfeit in the original package without the consumer becoming aware: the target customer of such a counterfeit compact disc will notice a missing or broken (self-destructed) label, and conclude that the compact disc""s authenticity has been compromised.
Difficulties arise, however, if a sophisticated counterfeiter uses a counterfeit OVD label. In such cases, it may be difficult to tell, by simply looking at the product, if the OVD label is genuine. A method of testing for the genuine label comprises pulling the seal to determine if it self-destructs into patterned pieces. If there is such a patterned breakage, the tester knows the label was genuine. Unfortunately the tester also has ruined or at least lessened the value of the labelled product. In the example above, even if the genuine compact disc can be recycled back to the manufacturer for repackaging with a new label, significant value has been destroyed.
The present invention provides an efficient and cost-effective enhancement of such tamper-apparent authenticity labels. The improvement lies in (i) allowing the inspection of self-destruct labels without actually causing them to self-destruct, and (ii) permitting the controlled, patterned self-destruction of the label incorporated the OVD. As metioned in the Background section, xe2x80x9cOVDxe2x80x9d includes, but is not limited to, diffraction gratings, exelgrams, kinegrams and/or holograms.
The security label of the present invention includes an outer film layer (i.e., the layer closest to the consumer and furthest from the article being sealed and authenticated) above an OVD-containing layer. An xe2x80x9cinkxe2x80x9d is printed below the outermost film layer but above the OVD-containing layer. The ink, containing a fluorescent taggant, is printed in a pattern, visible under ultraviolet light, but virtually invisible to the unaided eye. By shining an ultraviolet light on the seal, an inspector can determine whether the OVD label is genuine or counterfeit. The appearance of a fluorescent pattern confirms authenticity, while the absence of a fluorescent pattern leads the inspector to question authenticity.
Moreover, simply printing the fluorescent ink above the film layer will not circumvent this security feature. This is because the fluorescent ink lies below the film layer of the label, and there is no printed ink above the surface of the label. Accordingly, an inspector can determine, by scratching the surface of the label, if someone has attempted to approximate the fluorescent pattern in the genuine label by printing fluorescent ink above the surface of the label.
Importantly, a counterfeiter also cannot simply peel back the film layer of the label and then print fluorescent ink, as this would cause the label to self-destruct. This is due to a further security feature of the invention: the ink""s taggant is mixed with an oligomer which causes the ink to be releasable. The film layer binds to the ink and, where there is no ink (i.e., the xe2x80x9cspacesxe2x80x9d in the ink pattern), to the OVD-containing layer. Separating the film from the article causes the ink also to be separated, and also causes those portions of the OVD layer contacting the film (at the pattern""s spaces) to be separated. The portions of the OVD layer contacting the ink, but not the film, are xe2x80x9creleasedxe2x80x9d by the ink and thus not separated. Once separation occurs, the film cannot be re-adhered to the article. Further, because only those portions of the OVD layer in contact with the film are separated, the OVD image will self-destruct in a pattern substantially identical to the printed pattern. A separated label, and thus a compromised article, is easily detectable by the pattern broken OVD images and the non-adhesion of the film to the article.
Various other objects of the present inventions will become readily apparent from the ensuing detailed description and drawings.